{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,18]],"date-time":"2026-08-18T04:28:24Z","timestamp":1787027304865,"version":"build-2736575974"},"reference-count":15,"publisher":"Springer Science and Business Media LLC","issue":"1","license":[{"start":{"date-parts":[[2026,6,12]],"date-time":"2026-06-12T00:00:00Z","timestamp":1781222400000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0"},{"start":{"date-parts":[[2026,8,18]],"date-time":"2026-08-18T00:00:00Z","timestamp":1787011200000},"content-version":"vor","delay-in-days":67,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0"}],"content-domain":{"domain":["link.springer.com"],"crossmark-restriction":false},"short-container-title":["BMC Anesthesiol"],"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>This study aimed to compare the percentage of local anesthetic spread into the obturator canal between the nerve stimulation-guided interadductor approach (NS-INTAD) and the ultrasound-guided interadductor approach (US-INTAD), and to evaluate anatomical factors influencing the effectiveness of the obturator nerve block (ONB).<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>\n                      Eighty patients scheduled for transurethral resection of bladder tumor were randomized to receive either NS-INTAD (\n                      <jats:italic>n<\/jats:italic>\n                      \u2009=\u200940) or US-INTAD (\n                      <jats:italic>n<\/jats:italic>\n                      \u2009=\u200940). In the lithotomy position, a mixture of local anesthetic and contrast medium was injected via the interadductor approach from the medial thigh. Injectate spread into the obturator canal was assessed by fluoroscopy, and the success rate and injection volume were compared between groups.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      Enhancement in the obturator canal was observed in 75% of patients in the NS-INTAD group and 90% in the US-INTAD group. Although the percentage was higher in the US-INTAD group, the difference was not statistically significant (\n                      <jats:italic>P<\/jats:italic>\n                      \u2009=\u20090.139). The volume of local anesthetic used did not differ significantly between groups (\n                      <jats:italic>P<\/jats:italic>\n                      \u2009=\u20090.07). In patients where the posterior branch of the obturator nerve coursed between obturator externus muscle fascicles, local anesthetic propagation into the obturator canal appeared limited.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>The percentage of injectate spread into the obturator canal tended to be higher with US-INTAD than with NS-INTAD. Our findings suggest that the lithotomy-position approach facilitates more cephalad local anesthetic spread than the supine-position approach. Furthermore, the development of the superior fascicle of the external obturator muscle appears to be an anatomical factor that inhibits injectate spread into the obturator canal.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Trial registration<\/jats:title>\n                    <jats:p>UMIN Clinical Trials Registry (UMIN-CTR) UMIN000027762; registered 15 June 2017.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1186\/s12871-026-04008-2","type":"journal-article","created":{"date-parts":[[2026,6,12]],"date-time":"2026-06-12T06:14:55Z","timestamp":1781244895000},"update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Ultrasound versus nerve stimulation-guided interadductor approach for obturator nerve block: evaluation of injectate spread into the obturator canal in a randomized controlled trial"],"prefix":"10.1186","volume":"26","author":[{"given":"Tetsuya","family":"Uchino","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Masahiro","family":"Miura","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Chihiro","family":"Shingu","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Toshitaka","family":"Shin","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kenichiro","family":"Tomonari","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Shigekiyo","family":"Matsumoto","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"297","published-online":{"date-parts":[[2026,6,12]]},"reference":[{"key":"4008_CR1","doi-asserted-by":"publisher","first-page":"89","DOI":"10.2535\/ofaj1936.69.2-3_89","volume":"69","author":"E Nakamura","year":"1992","unstructured":"Nakamura E, Masumi S, Miura M, Kato S, Miyauchi R. A supernumerary muscle between the adductors brevis and minimus in humans. Okajimas Folia Anat Jpn. 1992;69:89\u201398. https:\/\/doi.org\/10.2535\/ofaj1936.69.2-3_89.","journal-title":"Okajimas Folia Anat Jpn"},{"key":"4008_CR2","doi-asserted-by":"publisher","first-page":"103","DOI":"10.2535\/ofaj.80.103","volume":"80","author":"M Yatsunami","year":"2004","unstructured":"Yatsunami M, Tai T, Irie Y, Ogawa K, Miyauchi R. A morphological study on the human obturator externus muscle with reference to anomalous muscle and anomalous fasciculus originating from the obturator externus muscle. Okajimas Folia Anat Jpn. 2004;80:103\u201314. https:\/\/doi.org\/10.2535\/ofaj.80.103.","journal-title":"Okajimas Folia Anat Jpn"},{"key":"4008_CR3","doi-asserted-by":"publisher","first-page":"495","DOI":"10.1007\/s00276-008-0358-x","volume":"30","author":"S Kendir","year":"2008","unstructured":"Kendir S, Akkaya T, Comert A, Sayin M, Tatlisumak E, Elhan A, Tekdemir I. The location of the obturator nerve: a three-dimensional description of the obturator canal. Surg Radiol Anat. 2008;30:495\u2013501. https:\/\/doi.org\/10.1007\/s00276-008-0358-x.","journal-title":"Surg Radiol Anat"},{"key":"4008_CR4","doi-asserted-by":"publisher","first-page":"33","DOI":"10.1097\/AAP.0b013e3181933b51","volume":"34","author":"S Anagnostopoulou","year":"2009","unstructured":"Anagnostopoulou S, Kostopanagiotou G, Paraskeuopoulos T, Chantzi C, Lolis E, Saranteas T. Anatomic variations of the obturator nerve in the inguinal region: implications in conventional and ultrasound regional anesthesia techniques. Reg Anesth Pain Med. 2009;34:33\u20139. https:\/\/doi.org\/10.1097\/AAP.0b013e3181933b51.","journal-title":"Reg Anesth Pain Med"},{"key":"4008_CR5","doi-asserted-by":"publisher","first-page":"13","DOI":"10.1136\/rapm-00115550-199318010-00003","volume":"18","author":"MR Wassef","year":"1993","unstructured":"Wassef MR. Interadductor approach to obturator nerve blockade for spastic conditions of adductor thigh muscles. Reg Anesth. 1993;18:13\u20137.","journal-title":"Reg Anesth"},{"key":"4008_CR6","first-page":"168","volume-title":"Chapter V: Blocking of Spinal Nerves","author":"G Labat","year":"1922","unstructured":"Labat G. Regional anesthesia. Its technique and clinical application. Chapter V: Blocking of Spinal Nerves. Philadelphia and London: WB Saunders; 1922. pp. 168\u2013299."},{"key":"4008_CR7","doi-asserted-by":"publisher","first-page":"291","DOI":"10.1111\/anae.13336","volume":"71","author":"T Yoshida","year":"2015","unstructured":"Yoshida T, Onishi T, Furutani K, Baba H. A new ultrasounds guided pubic approach for proximal obturator nerve block: clinical study and cadaver evaluation. Anaesthesia. 2015;71:291\u20137. https:\/\/doi.org\/10.1111\/anae.13336.","journal-title":"Anaesthesia"},{"key":"4008_CR8","doi-asserted-by":"publisher","first-page":"357","DOI":"10.1097\/AAP.0000000000000587","volume":"42","author":"TD Nielsen","year":"2017","unstructured":"Nielsen TD, Moriggl B, S\u00f8balle K, Kolsen-Petersen JA, B\u00f8rglum J, Bendtsen TF. A cadaveric study of ultrasound-guided subpectineal injectate spread around the obturator nerve and its hip articular branches. Reg Anesth Pain Med. 2017;42:357\u201361. https:\/\/doi.org\/10.1097\/AAP.0000000000000587.","journal-title":"Reg Anesth Pain Med"},{"key":"4008_CR9","doi-asserted-by":"publisher","first-page":"569","DOI":"10.1016\/j.redare.2023.10.002","volume":"70","author":"S Diwan","year":"2023","unstructured":"Diwan S, Feigl G, Nair A. Sonographic obturator nerve block at level of superior pubic ramus: A thiel based cadaveric investigation with latex. Rev Esp Anestesiol Reanim (Engl Ed). 2023;70:569\u201374. https:\/\/doi.org\/10.1016\/j.redare.2023.10.002.","journal-title":"Rev Esp Anestesiol Reanim (Engl Ed)"},{"key":"4008_CR10","doi-asserted-by":"publisher","first-page":"383","DOI":"10.1007\/s00540-022-03055-6","volume":"36","author":"T Uchino","year":"2022","unstructured":"Uchino T, Miura M, Matsumoto S, Shingu C, Shin T, Tomonari T. Comparison of three obturator nerve block techniques for injectate spread into the obturator canal: a randomized controlled trial. J Anesth. 2022;36:383\u20139. https:\/\/doi.org\/10.1007\/s00540-022-03055-6.","journal-title":"J Anesth"},{"key":"4008_CR11","doi-asserted-by":"publisher","first-page":"123","DOI":"10.1007\/s005400200006","volume":"16","author":"M Kakinohana","year":"2002","unstructured":"Kakinohana M, Taira Y, Saitoh T, Hasegawa A, Gakiya M, Sugahara K. Interadductor approach to obturator nerve block for transurethral resection procedure: comparison with traditional approach. J Anesth. 2002;16:123\u20136. https:\/\/doi.org\/10.1007\/s005400200006.","journal-title":"J Anesth"},{"key":"4008_CR12","doi-asserted-by":"publisher","first-page":"236","DOI":"10.1213\/ANE.0b013e318237fb40","volume":"114","author":"AM Taha","year":"2012","unstructured":"Taha AM. Brief reports: ultrasound-guided obturator nerve block: a proximal interfascial technique. Anesth Analg. 2012;114:236\u20139. https:\/\/doi.org\/10.1213\/ANE.0b013e318237fb40.","journal-title":"Anesth Analg"},{"key":"4008_CR13","doi-asserted-by":"publisher","first-page":"em426","DOI":"10.29333\/ejgm\/12592","volume":"20","author":"E Buyukfirat","year":"2023","unstructured":"Buyukfirat E, Binici O, Duran E, Pehlivan B, Atlas A, Erol MK, Babacan S. Can different positions facilitate block application in ultrasound-guided obturator nerve block? A prospective comparative study. Electron J Gen Med. 2023;20:em426.","journal-title":"Electron J Gen Med"},{"key":"4008_CR14","doi-asserted-by":"publisher","first-page":"652","DOI":"10.1007\/s00540-024-03434-1","volume":"39","author":"T Yoshida","year":"2025","unstructured":"Yoshida T, Nakano Y, Kitada M, Nakamoto T. Ultrasound-guided obturator nerve block technique at the distal end of the obturator canal: case series and cadaver evaluation. J Anesth. 2025;39:652\u20136. https:\/\/doi.org\/10.1007\/s00540-024-03434-1.","journal-title":"J Anesth"},{"key":"4008_CR15","doi-asserted-by":"publisher","unstructured":"Labandeyra H, Goffin P, Riera R, Vallejo A, Prats-Galino A, Sala-Blanch X. Obturator canal block: an anatomical study. Reg Anesth Pain Med. 2024;rapm\u20132024\u2013105901. https:\/\/doi.org\/10.1136\/rapm-2024-105901.","DOI":"10.1136\/rapm-2024-105901"}],"container-title":["BMC Anesthesiology"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/link.springer.com\/article\/10.1186\/s12871-026-04008-2","content-type":"text\/html","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/link.springer.com\/content\/pdf\/10.1186\/s12871-026-04008-2.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/link.springer.com\/content\/pdf\/10.1186\/s12871-026-04008-2.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,8,18]],"date-time":"2026-08-18T03:38:18Z","timestamp":1787024298000},"score":1,"resource":{"primary":{"URL":"https:\/\/link.springer.com\/10.1186\/s12871-026-04008-2"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,6,12]]},"references-count":15,"journal-issue":{"issue":"1","published-online":{"date-parts":[[2026,12]]}},"alternative-id":["4008"],"URL":"https:\/\/doi.org\/10.1186\/s12871-026-04008-2","relation":{},"ISSN":["1471-2253"],"issn-type":[{"value":"1471-2253","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,6,12]]},"assertion":[{"value":"10 April 2026","order":1,"name":"received","label":"Received","group":{"name":"ArticleHistory","label":"Article History"}},{"value":"5 June 2026","order":2,"name":"accepted","label":"Accepted","group":{"name":"ArticleHistory","label":"Article History"}},{"value":"12 June 2026","order":3,"name":"first_online","label":"First Online","group":{"name":"ArticleHistory","label":"Article History"}},{"value":"This study was approved by the Institutional Review Board of the Faculty of Medicine, Oita University (Oita, Japan) (Approval No. B16-040). The trial was registered in the University Hospital Medical Information Network Clinical Trials Registry (UMIN-CTR; Trial No. UMIN000027762). Written informed consent was obtained from all participants before enrollment. All procedures were performed in accordance with the Declaration of Helsinki and relevant institutional guidelines and regulations.","order":1,"name":"Ethics","label":"Ethics approval and consent to participate","group":{"name":"EthicsHeading","label":"Declarations"}},{"value":"Not applicable.","order":2,"name":"Ethics","label":"Consent for publication","group":{"name":"EthicsHeading","label":"Declarations"}},{"value":"The authors declare no competing interests.","order":3,"name":"Ethics","label":"Competing interests","group":{"name":"EthicsHeading","label":"Declarations"}}],"article-number":"501"}}